Polyether ether ketone (PEEK) is a thermoplastic material commonly used in the manufacture of implants. PEEK implants provide many advantages as compared to implants made of metal, such as titanium. For example, PEEK implants have a modulus of elasticity that is more similar to the modulus of elasticity of bone, and therefore, PEEK implants provide for improved biomechanics when implanted into the body. In addition, PEEK, implants are radiolucent (i.e., partly or wholly permeable to radiation). This allows for improved assessment of bony fusion and/or reappearance of cancer.
Because PEEK implants are radiolucent, it is more difficult to intraoperatively determine the exact implant position and orientation. One solution to the problem above is to provide an implant made of a semi-radiolucent PEEK material that is partially visible with a C-arm x-ray system, for example. However, when the PEEK implant is semi-radiolucent, it becomes more difficult to assess bony fusion and/or reappearance of cancer. Another solution to the problem above is to provide radio-opaque internal markers within the PEEK implants that define the edges of the PEEK implants. The markers appear as fiducial markers in the image captured by the C-arm x-ray system and facilitate visual estimation of implant position and orientation. However, even using PEEK implants with radio-opaque markers, it is still difficult to accurately estimate implant position and orientation because the exact distance between the markers and the edges of the implants are not captured in the image.